Open Cluster M47 (NGC 2422), type 'd', in Puppis

Right Ascension 07 : 36.6 (h:m); Declination -14 : 30 (deg:m); Distance 1.6 (kly); Visual Brightness 5.2 (mag); Apparent Dimension 30.0 (arc min)

Open cluster M47 is a coarse cluster of bright stars, and contains about 50 stars in a region 12 light years in diameter; in the central portion, the stellar density is about 16 stars per cubic parsec while the average density of the whole cluster is only 0.62 stars per cubic parsec, according to Wallenquist (as quoted by Kenneth Glyn Jones). Its distance is about 1,600 light years (values scatter from 1,560 to 1,750 light years), so that the stars of M47 appear scattered over an area in the sky of the same size as the full moon, 30 arc minutes. The cluster's Trumpler type is given discordantly as II,3,m (Glyn Jones), I,3,m (Götz), and III,2,m (Sky Catalog 2000). The brightest star is of spectral class B2 and mag 5.7, the overall population resembles that of the Pleiades. It also contains two orange K giants with luminosity of about 200 times that of the Sun each.

Source and more: SEDS

M46 - M47 - NGC2423 - NGC2425: A Quartet of Open Clusters.
March 20, 2009 18:44 - 19:14 UT.
Imaging: 135mm SLR Photolens, ATK16IC camera with Astronomik LRGB filters.
Exposures: Lum: 5x90s [1x1]; RGB 5x30s [2x2]; unguided.

March 17, 2009 19:21 - 21:00 UT.
Imaging: William Optics Zenithstar 80 ED II APO with Meade 3.3 Focal Reducer at f/3 [focal length 240 mm], ATK16IC camera, Astronomik LRGB filters.
Exposures: L: 22x75s [1x1]; RGB 5x35s [2x2]; all unguided.